1. Technical Field
The present invention relates to a liquid crystal display device provided with liquid crystals and to an electronic apparatus including the liquid crystal display device provided with liquid crystals.
2. Description of the Related Art
There have been developed systems (modes) for driving liquid crystals, including a liquid crystal driving system that uses an electric field generated in a longitudinal direction between substrates, that is, a longitudinal electric field. Examples of a liquid crystal display device that drives liquid crystals using a longitudinal electric field include, but are not limited to, longitudinal-electric-field liquid crystal display devices provided with a twisted nematic (TN) system, a vertical alignment (VA) system, an electrically controlled birefringence (ECB) system, etc. As disclosed in Japanese Patent Application Laid-open Publication No. 2008-52161 (JP-A-2008-52161), there has also been developed a liquid crystal driving system that uses an electric field generated in a direction parallel to substrates (lateral direction), that is, a lateral electric field. Examples of a liquid crystal display device that drives liquid crystals using a lateral electric field include, but are not limited to, lateral-electric-field liquid crystal display devices provided with a fringe field switching (FFS) system, an in-plane switching (IPS) system, etc.
In the IPS mode, a first electrode and a second electrode are provided on the same layer, and an electric field is generated mainly in a direction parallel to the substrate surface. This configuration makes the electric field unlikely to be generated in an area on the first electrode, thereby making liquid crystal molecules in the area unlikely to be driven.
In the FFS mode, a pixel electrode and a common electrode overlap in a direction perpendicular to the substrate surface with a dielectric film interposed therebetween. This configuration generates an electric field extending mainly in a direction oblique to the substrate surface or a parabolic electric field (also referred to as a fringe electric field). As a result, liquid crystal molecules in an area on the pixel electrode are likely to be driven. In other words, the FFS mode can provide a higher aperture ratio than the IPS mode does.
The lateral-electric-field liquid crystal display device generates an electric field between the first electrode and the second electrode in a direction parallel to the substrate, thereby rotating the liquid crystal molecules in a plane parallel to the substrate surface. The liquid crystal display device performs display using a change in the light transmittance corresponding to the rotation of the liquid crystal molecules. Such lateral-electric-field liquid crystal display devices are required to increase the response speed of the liquid crystals.
Japanese Patent Application Laid-open Publication No. 2010-145825 describes the fact that the response speed of liquid crystals varies depending on the thickness of a liquid crystal layer and describes a liquid crystal display device in a VA mode that can prevent coloration by equalizing the response speeds of respective colors. Japanese Patent Application Laid-open Publication No. 2013-109309 (JP-A-2013-109309) describes a liquid crystal display device having a higher response speed of liquid crystals than that of the liquid crystal display device described in JP-A-2008-52161.
The inventors found that, while the liquid crystal display device described in JP-A-2013-109309 can increase the response speed of liquid crystals in a pixel as a whole, it is necessary to stabilize the orientation of the liquid crystals in respective sub-pixels corresponding to a plurality of different color areas.
For the foregoing reasons, there is a need for a liquid crystal display device that can achieve a higher response speed of the entire pixel and higher orientation stability in each sub-pixel to improve display quality in a display surface.